Radio Network Controller (RNC), which is used to control the Nodes connected to it such as Node Bs, is a governing element in the Universal Mobile Telecommunications System (UMTS) radio access network (UTRAN). A RNC node is generally designed as cluster architecture in which more than one control unit are arranged to obtain a good scalability.
A conventional RNC system with cluster architecture is schematically shown in FIG. 1. The conventional RNC system 1 comprises work unit cluster 10, a transport unit 120, and an O&M (i.e., operation and maintenance) management unit 130; where the work unit cluster 10 includes an administrating unit 100 and a plurality of control units 110.
The control unit, comprising a Node B handling element to manage the cell and common channels, paging, system information distribution and so on, a UE handling element to handle the radio connection setup, radio bearer setup and packet scheduling, and a resource measurement element to measure for example the CPU/memory utilization degree of the control unit, is employed to control part of the radio network which the RNC system governs; for example, it is used to control the radio resource, mobility, handover and the like.
The administrating unit 100 serving as the load balancer of the RNC work unit cluster distributes the requests from the external devices to the control units to achieve a relative balanced load distribution among those control units. The partition element 101 in the administrating unit 100 is used to partition the Node Bs termination among the control units based on the control unit performance status, thereby makes each control unit maintain a relative equal load for Node B related requests. The distribution element 102 as shown in FIG. 1 is used to distribute newly received requests among the control units. The monitor element 103 is utilized to collect the status information from the resource measurement element of each control unit and transfer the collected information to the partition element 101 and the distribution element 102.
The control unit, which is also known as user plane board(s) or control plane board(s) etc, is generally embodied as electrical circuit board(s), such as printed circuit board, in which each board can include one or more processers. Also, the administrating unit can be one or several electrical circuit boards, which comprise at least one processor. The work unit cluster means a cluster architecture which comprises more than two control units and at least one administrating unit.
The O&M management unit 130 is used as a node manager which provides the administrator with a GUI, and the transport unit 120 implements ATM (i.e. Asynchronous Transfer Mode)/IP (i.e. Internet Protocol) transport functionality for external communication tunnel towards CN and Node B.
The RNC system as above-mentioned is deployed to maintain a peak load status which means be kept running at all time. However, it statically shows that the average radio resource utilization at low traffic time (such as 0:00-8:00 of a day) is 1/7 of that at high traffic time (such as 16:00-24:00 of a day). That is, compared to operate at the high traffic time, the control unit of the RNC system at low traffic time usually waits for the external requests. However, the conventional RNC system still keeps all RNC control units, including those waiting for the external requests, fully running as at the high traffic time.